Muhammad Taqiyuddin Mawardi Ayob

Enhanced Photocatalytic Performance of NiO-Decorated ZnO Nanowhiskers for Methylene Blue Degradation

ZnO nanowhiskers were used for photodecomposition of methylene blue in aqueous solution under UV irradiation. The rate of methylene blue degradation increased linearly with time of UV irradiation. 54% of degradation rate was observed when the ZnO nanowhiskers were used as photocatalysts for methylene blue degradation for 80 min under UV irradiation. The decoration of p-type NiO nanoparticles on n-type ZnO nanowhiskers significantly enhanced photocatalytic activity and reached 72% degradation rate of methylene blue by using the same method. NiO-decorated ZnO was recycled for second test and shows 66% degradation from maximal peak of methylene blue within the same period. The increment of photocatalytic activity of NiO-decorated ZnO nanowhiskers was explained by the extension of the electron depletion layer due to the formation of nanoscale p-n junctions between p-type NiO and n-type ZnO. Hence, these products provide new alternative proficient photocatalysts for wastewater treatment.

Effect of triethanolamine:ethylenediamine ratios on CuO nanoparticles prepared by ultrasound irradiation

Coral-spherical-shaped of copper oxide nanoparticles have been successfully synthesized with different ratios of triethanolamine:ethylenediamine surfactant under ultrasonic condition. By controlling the amplitude of the ultrasonic radiation and concentration of metal salt precursors and surfactant, the formation of CuO nanospheres was obtained. Energy dispersive X-ray spectrum confirmed that Cu and O are the only elementary components present with a ratio of approximately 1:1. Furthermore, X-ray powder diffraction spectra for all the examined ratios of CuO showed well crystalline structures. UV-Vis spectroscopy was utilized to estimate the band gap energies of the CuO nanoparticles produced, which were found to be in the range of 2.74 eV to 2.95 eV. The field emission scanning electron micrographs of these nanospheres showed that their dimensions were in the range of 5-30 nm. These results indicate that the triethanolamine:ethylenediamine ratio plays an important role in the formation of different sized CuO nanoparticles, displaying a decrement in particle size with the increment in amount of triethanolamine ratios. This might be the key to synthesizing nanoparticles with specific sizes for various applications.

Synthesis and Characterization of ZnO, CuO and CuO/ZnO Nanostructures by a Novel Sol-Gel Route under Ultrasonic Conditions

Great interests in metallic oxides have emerged because of the possibility to modify the properties of these materials for different applications such as catalysis or sensors. In this work, CuO, ZnO and CuO-ZnO nanoparticles were prepared by a novel sol-gel route under ultrasonic condition using triethanolamine as an emulsifying surfactant. Fine powders were obtained when the pH of the sols were increased to 13 using NaOH. Particle sizes of the produced oxide materials were in the range of 3-4 nm, 40-50 x 100-150 nm (diameter x length) and 100-200 nm for CuO, ZnO and CuO-ZnO, respectively. The molar ratio of triethanolamine to metal nitrate precursors was set at 2:3. TEM micrographs of these particles were obtained to elucidate the morphology of the nanoparticles. Experimental results show that the band gap energies (Eg) for CuO, ZnO and CuO-ZnO were found to be 2.71, 3.35 and 2.82 eV, respectively.

Gamma irradiation induced method in preparation of Gd2O2S: Eu3+ phosphors: The effect of dose towards luminescent properties

A novel gamma irradiation induced synthesis method of Gd2O2S:Eu3+ phosphors was investigated in the presence of cetyltrimethylammonium bromide (CTAB). The effect of irradiation doses (50-150kGy) on structural and morphology analysis as well as luminescence properties were characterized by X-ray diffraction (XRD), field emission scanning microscopy (FESEM) and photoluminescence spectrometer (PL). The results show that gamma radiation is potentially induced formation of Gd2O2S:Eu3+ phosphors from radiation reduction and/or precipitation of insoluble compounds as the hexagonal phase structure was formed without any impurities as proven in XRD pattern. The morphologies were observed that the obtained Gd2O2S:Eu3+ phosphors possess sphere structure with smooth surface at 100 kGy irradiated dose. PL spectroscopy reveals that the strongest red emission peaks is located at 626 nm under 325 nm light excitation, which corresponds to 5D0→7F2 transition of Eu3+ ions. An optimized dose for excellent luminescent was observed at 100 kGy. The results suggested that the Gd2O2S:Eu3+ phosphors may have a beneficial approach in field of imaging device or media.

Study on the Effect of γ-Irradiation on Gadolinium Oxysulfide Nanophosphors (Gd2O2S-NPs)

Gadolinium oxysulfide nanophosphors (Gd2O2S-NPs) have been successfully synthesized using γ-irradiation and hydrogenation treatment. The primary stage of Gd2O2S-NPs synthesis was carried out using various doses of γ-irradiation to form diverse sizes of Gd2(SO4)3 precursor, followed by hydrogenation treatment at 900°C for 2 hours to form Gd2O2S-NPs. Then, the nanophosphors were characterized for the structure, morphology, and luminescence properties through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and photoluminescence spectrometer (PL). Pure hexagonal phase of Gd2O2S-NPs was obtained with high crystallinity and without any impurities. The morphologies were observed from grain-like nanostructures transformed to spherical shape as the irradiation dose reached 40 kGy. Besides, Gd2O2S-NPs which were prepared at highest irradiation dose of 40 kGy show highest intensity of emission peak at 548 nm and corresponded to Stark level transition from the state of Gd3+ ion. It can be emphasized that the different doses of γ-irradiation influenced the nucleation event of Gd2(SO4)3 precursor thus affecting the morphology and size particles of Gd2O2S-NPs. Hence, from the results, it can be suggested that Gd2O2S-NPs can be a promising host for optical applications.

Interaction between silicon dioxide and dipalmitoylphosphatidylcholine (DPPC) vesicles

Many of the cellular process depend on the ability of the membrane to separate areas while allowing exchange and tightly regulated transport of material within and across the membrane to occur, which is the driving principle behind cell communication. The complexity of biological membranes has motivated the development of a wide variety of simpler model systems whose size, geometry and composition can be tailored with precision. This study was conducted to investigate the interactions between silica nanoparticles and Dipalmitoylphosphatidylcholine (DPPC) vesicles. The size range of DPPC vesicles formed was from 50 to 150 nm. Concentration of silica added to the vesicles was varied from 0.25 to 1.5 mg/ml. The change in vesicle size distribution, localization and positioning of silica nanoparticles in vesicles was studied via transmission electron microscopy (TEM) and differential scanning calorimetry (DSC).

Effect of gamma irradiation on hyaluronic acid and dipalmitoylphosphatidylcholine (DPPC) interaction

DPPC lipids are the major component constituting the biological membrane, and their importances in various physiological functions are well documented. Hyaluronic acid (HA) in the synovial joint fluid functions as a lubricant, shock absorber and a nutrient carrier. Gamma irradiation has also been found to be effective in depolymerizing and cleaving molecular chains related to free radicals, thus extends with changes in chemical composition as well as its physiological functions. This research are conducted to investigate the hyaluronic acid (HA) and 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) interaction in form of vesicles and its effect to gamma radiation. The size of DPPC vesicles formed via gentle hydration method is between 100 to 200 nm in diameter. HA (0.1, 0.5 and 1.0 mg/ml) was added into the vesicles and characterized by using TEM to determine vesicle size distributions, fusion and rupture of DPPC structure. The results demonstrated that the size of the vesicles approximately between 200 to 300 nm which caused by vesicles fusion with HA and formed even larger vesicles. After being irradiated by 0 to 200 Gy, the size of vesicles decreased as HA was degraded. To elucidate the mechanism of these effects, FTIR spectra were carried out and have shown that at absorption bands at 1700–1750 cm−1 due to formation of carboxylic acid and leads to alteration of HA structure.

Characteristics of ZnO nanostructures produced with [DMIm]BF4 using ultrasonic radiation

Great interests in metallic oxides have emerged because of the promising properties of these materials for various applications such as solar cells and sensors. ZnO nanostructures with different morphologies were successfully synthesized from Zn(CH3COO)2•2H2O, NaOH and room temperature ionic liquid (RTIL) 1-decyl-3-methylimidazolium tetrafluoroborate, [DMIm][BF4] with ultrasound irradiation. Parameters such as the effect of sonication time (30, 60 and 90 minutes) and Zn(Ac)2 precursor to [DMIm][BF4] ratios of 3:5, 5:5 and 5:3 were investigated. X-ray diffraction patterns revealed that the ZnO nanocrystals were hexagonal zincite crystalline in structure. The band gap energies (Eg) were estimated to be 3.35-3.55 eV from the UV-Visible spectrum. The solution with the highest ratio of Zn was analysed with photoluminescence spectroscopy, which exhibited peaks at 362, 403, 468 and 539 nm, at room temperature. The micrographs of field emission scanning electron microscopy and transmission electron microscopy sho...